Gate-actuated operating mechanism for trucking sills



Feb le 1960 E. E. ALEXANDER GATE-ACTUATED OPERATING MECHANISM FOR TRUCKING sms Filed oct. 14, 1957 Y i l l5 GATE-ACTUATED OPERATING MECHANISM FOR TRUCKING SILLS Elisha E. Alexander, Chicago, lll.

Applicaton October 14, 1957, Serial No. 689,894

Claims. (Cl. 20-19) This invention relates to trucking sills for use With elevators and, more particularly, is concerned with an opera'ting mechanism for automatically positioning a trucking sill in response to the movement of a gate that shifts vertically from a lower position wherein it blocks the entrance to the elevator to an upper position wherein it is bridged above the entrance to the elevator.

In the usual arrangement, a certain operating clearance is provided between an elevator and the structure'surrounding the elevator hatch yso that a horizontal gap exists between the floor of 'the elevator and the floors or platforms bordering the hatch. Trucking sills for bridging these gaps are known, but for maximum safety and convenience, it is important that the sills and elevator entrance gate operate conjointly so 'that as the gate moves from its blocking position within the entrance to its bridging position above the entrance, the sill will move from a4 blocking position wherein it may extend vertically to cooperate with the gate in blocking olf the elevator entrance to a bridging position wherein it spans the clearance gap. i

Such an arrangement for use with a horizontally split door having upper and lower door sections shiftable in opposite vertical directions is shown in my U.S. Patent 2,473,125.

The principal object of the present invention is to provide an operating mechanism `for automatically controlling the positioning of a trucking sill in accordance with the movements of a single-section gate or door that shifts vertically between a lower blocking position and an upper bridging position.

Another object is to provide an operating mechanism arranged to undergo overcenter travel as it approaches its opposite limits of movement to prevent displacement of the sill except upon actuation by the gate.Y

Still another object is to provide a counterbalanced sill arrangement so that as the sill approaches its bridging position, its Weight predominates and carries the operating mechanism overcenter independently of the gate but as the sill approaches its upraised or blocking position, the counterweight predominates and carries the operating mechanism overcenter independently of the gate.

Other objects and advantages will become apparent during the course of 'the following description.

In the accompanying drawings forming a part of this specification and in which like numerals are employed to designate like parts throughout the same:

Fig. 1 is a plan view through the entrance to an elevator with certain parts of one of the chambered door posts broken away;

Fig. 2 is a side view through one of the door posts with parts broken away to illustrate the arrangement of the operating mechanism when the trucking sill is in its bridging position; and

Fig. 3 is a view similar 'to Fig. 2 except with the trucking sill shown in its upraised, or blocking, position in the elevator entrance.

For purposesV of disclosure, the trucking sill- 10 and hatch gate 11 are shown appli-ed to a supporting structure that has a floor'` 12 bordering a hatchway in which the oor 13 of an elevator car is vertically shiftable. The sill 10 is connected to the building door by suitable hinges 14 for reversibleswinging` movement in the entrance to the elevator between a lower, or horizontal, bridging position (see Fig. 2), wherein it spans the juxtaposed edges of the oors 12 and 13 and an upraised, or vertical, blocking position (see Fig. 3), wherein it closes oli the bottom region of the entrance.

Such a sill arrangement is particularly useful with gates that include downwardly-projecting legs 15 at their opposite sides for establishing supporting engagement with the door. Thus, with the gate legs 15 engaging the iioor 12,V the large center region of the gate, as indicated by dotted lines 16 in Fig. 3, is spaced well above the oor. The sill 10, when inits upraised position, is preferably arranged to block 'substantially the entire region between the iioor'and the bottom of the gate 11 and since the sill is locked against accidental displacement from either of its extreme positions (as will be explained hereinafter), it protects the gate from being smashed by trucks, and

. it also prevents material from dropping or rolling into the elevator hatch.

As is apparent from Fig. 1, each end of the sill is provided with an operating mechanism. These mechanisms are identical, and a single description will suiice.

Each operating `mechanism includes an actuating arm or pawl 20 lixedly carried by one of the gate legs 15 to undergo substantially linear reciprocating vertical movementfor reversibly driving a sill-operating cam 21. The cam is mounted for swinging movement about a iixed pivot 22 to swing above and below an approximately central horizontal position. The swinging movement of the cam arm is limited by upper and lower stops 23 and 24 respectively. The cam portion itself is in the form of a fork 25 that opens towards the pawl 20, with the fork having a lower arm 26 engageable by the pawl during a portion of 'the downward movement of the gate 11 and an upper arm 27 engageable with the pawl during a portion of the upward movement of the gate. At an intermediate point the cam arm is pivoted to one end of a oating link 28, the opposite end of which is pivotally connected to a rigid operating rod 29"which is pivotally mounted to the sill, as shown at 30. The linkage arrangement includes a releasing link 31 mounted for swinging movement about a iixed pivot 32, With its free end pivoted to an intermediate point 33 of the lioating link 28.

It should be apparent that as the pawl 20 is carried downwardly by the gate 11, it engages the lower arm 26 of the fork-shaped cam and drives it from the position in which it is illustrated in Fig. 2, beyond its horizontal central position, and to a downwardly-inclined intermediateposition short of its lower limit of movement. At this intermediate position, the swinging movement of the cam carries the arm 26 `out of the line of action of the pawl, and further downward movement of the gate does not aiect the operating mechanism for the sill.

Similarly, when the gate is being raised, the pawl engages the upper arm 27 of the fork-shaped cam and drives it from the position in which it is illustrated in Fig. 3, through its horizontal central position, and to an upwardly-inclined intermediate position short of its upper limit of movement. At this latter intermediate position, the swinging movement of-the cam carries the arm 27 out of the line of action of the pawl and further upward movement of the gate does not aiect the operating mechanism for the sill.

To insure that the cam and sill complete their swinging movements, a counterweight 35 suspended from suitable sheaves 36 by means of a flexible chain 37 that connectsto the sill is `arranged to balance. withthe sill at a sill position approximately midway between its exf tremes of movement. a

Thus, during downward movements of the gate, the

sill islapproacling VVa vertical position under the inu'enceof the direct engagement betweeny the pawly 2^0 and the cam and the eifective lever arm of the centenof gravity of the sill with respect to the sill hinges 14 becomes quite small so that the counterweight 35 predominates andimposes -a force that carries the sill to its upper'limit position as determined by the limit stop- 231'which engages the cam;V Similarly, as the gate is being raised and the sill approaches its horizontal bridgingposition, the

effective lever arm of its center of gravity approach" ing a maximum so that the effect'of the sillpr'edominates over the counterweight and it completesits movement and 4carries the cam to its lower limit position. In being driven to its opposite limits of movement by` the counter# balancing facilities, the linkage system is carried over'- center, and it then becomes impossiblev to reversethe motion of the linkage except by engaging :the cam,with the pawl 20. It is apparent from a consideration `of, Figs, 2 vand 3 that the sill is, in eiect, locked in both Vits bridging and blocking positions. Direct forces onuthe sill are incapable of dislodging it from these positions.

The operating mechanisms are housed in'chambered door posts 40 thatilank the entrance to the velevator,I`v

Upper channel-shaped housings 41 are providedforthe counterweight 35, its sheaves 36 and operating chainv7. Thelinkage is mounted'in a suitable housing 42 and, for this purpose, aV vertical mounting plate 43-is secureddin placeinthe housing 42 to mount thevarious partsLpf'the linkage. For example, the sill-operating cam`21 yisulog,

cated on theinsidefaceof the `mounting plate whilegfthre, floating llink 28,foperating rod 29, and releasing link 31 arearranged4 on the outside face of themcunting plate 435.. The plate -43 is formed with an arcuate clearance` slot 44 through vwhich the connection 4 5 vbetween the cam and iioatinglinkextends. Thereleasing link is offset as indicated at 4.6, to provide the 'necessary clearance with the oating link 28. f

While, in the illustrated, preferred embodiment, the gate and sill are mounted on thevstructure thatsurrounds the elevator hatch, they could, if desired,both be mounted on the elevator itself, or, `by obvious modifications, could be mounted separately; for example, with the gate on the supporting Ystructure and with the sill on the elevator.

The invention is 'not limited to the disclosed linkage arrangement but ncludes'fobvious alternative arrangements apparent to those skilled in this art; howeventhe, simplicity and ruggedness of the disclosed arrangement offers" importantadvantages inasmuch as this equipment is subjected to frequent and rugged loading andfmust withstand such loading without requiring frequent maintenance.

I claim: y

1. In combination, a trucking sill shiftable through an entrance thatrdivides a floor bordering an elevator hatch and a iloor shiftable in the hatch to move between a blocking position in the entrance and a bridging polsi tion whereinit spans juxtaposed edges of said iloors, a single-section gate shiftable vertically in said entrance from a lower blocking position therein v, to a bridging position thereabove, and' an operating mechanism having driving means and, driven means drivingly connectedgto and'selectively actuating said driving means, said driven means being engageable with said gate and selectively responsive to the verticaldirection of movement thereof and said` driving means being engaged with said sill for moving said sill between its blocking and bridging positions conjointly with the movement of said gate between itslower blocking and yits upper bridge positionsrespfec! tively. i I* f' 2. Foruse with an elevator having a iloor shiftable vertically ina hatch, for approximately horizontal'.v alignment with a ioo'r bordering theV hatch and forming "an entrance'between juxtaposed edges of said floors, a truck`` said edges for swinging movement between a blocking position in said entrance nad a bridging position across said edges, a single-section gate shiftable vertically upward in said entrance from a lower blocking position wherein it is supported on one of said oors to an upper bridging position whei'ein'it is spaced above said lastmentioned Viioor, andan operating mechanism having driving'means Vand driven means drivingly `connected to and selectively actuating said driving means, said driven means being cngageable with said gate and selectively responsive to the vertical direction lof movement thereof and said driving means being engaged with said sill for moving said sill-between,itsblocking and bridging positions conjointly with the movement of said gate between its lower blocking and its upper bridging positions respectively.

3. The'arrangement of claim 2 wherein said operating mechanism includes a counterweight suspended to oppose movement ofsaid sill as`it moves from blocking position tob'ridging position, said counterweight balancing theI forceof .said sill when .said sill` is approximately interm'ediately between its blockingand bridging positions.

4. The combination with a trucking sill shiftable throughian entrance that .divides a Hoor borderingan ele` vater-hatch and a lloor shiftable in the hatch to move betgweena blocking position in the entrance and a bridging .position wherein it spans juxtaposed edges, of saidl iloors, anda ,single-section gate slhiyftarble vertically in said entrance, .between a :lower bloekir'lgposifofl, therein anda b-ridgingposition thereabove; o f an operating mechamsn, to; waving` said: Sill between its blevking .and bgislginagppsitons .conjointe lwith themovemef .0f ,Said sate s betw en its bleeking and bridging nositlons'respcmaints@ Q11 said estafa-zam having a ixdlpivt Peint atene and thereof @Swinging lavement abeutea Sub. stantially central horizontal positionand having a fork atI the other end thereof opening towards said pawl, saidy fork allovverfarm engageableiwith 'said pawl during a portionof the vertical downward movementof said gate and an upperarm engageablewit'h said pawl during a portion `of vertically upward movement of -said gate,

means of said operating mechanism includesl apawl connected ot said gate and revcrsibly shifta'ole in 'response to vertical movement thereof and wherein said driving means includesa sill-operating arm connected to said sill and shiftableto vary the positioning'thereof between the blocking andy bridging positions.

' 7. The` arrangement of claim 4 wherein said operating mechanism includes a counterwei'ght suspended to oppose movementy'of vsaid sill as it moves from blocking Vposition to bridging position, said counterweight balancing the forceuof said sill when said sill. is approximately intermediately between its blocking and bridging positions.

8. Iny combination, la truckinglsill pesitionableacro-ss a Lgap Abetvveeri/va"iixerlV licor bordering an elevator .hatch and van elevator-Hoor shiftableiit said hatch, said siii movable to*adblockingposition adjacent saiidf'gap 'and to a bridging, pcsitionpver Saidfsap, afork andfliiikassembly connected to said sill, as ingle-section gateshiftable vertically upward of said gap to open, anda pawlfastened to.said gate and` positioned tol engage said fork and actuateisaid link assembly to move saidsill to a ,bridging position when said gate is raised to an open. positionand to engage-saidiork'- and actuatesaidlink lassemblylto move said sill to a blocking position when said gate is lowered to a closed position.

9. The combination with a trucking sill positionable across a gap between a fixed oor border-ing an elevator hatch and an elevator oor shiftable in said hatch, and 1.1. single-section gate shiftable vertically upward of said gap to open; of an operating mechanism for moving said sill from a bridging position to a blocking position, said operating mechanism including a pawl mounted on said gate so as to engage a fork opening toward said pawl, said fork connected by a link assembly to said sill, said fork having one arm engageable with said pawl to drive said link assembly to shift said sill t a bridging position during vertical upward movement of said gate and a second arm engageable with said pawl to drive said link assembly to shift said sill to a blocking position during vertical downward movement of said gate.

10. The combination with a trucking sill positionable across a gap between a fixed oor bordering an elevator hatch and an elevator oor shiftable in said hatch, and a single-section gate shiftable vertically upward of said gap to open; of an operating mechanism for moving said sill from a blocking position to a bridging position, said operating mechanism :including a pawl mounted on said vertically shiftable gate, a fork opening toward said pawl, a link assembly land a sill connterweight, said fork being engageable with said pawl to drive said link assembly, oppose said counterweight, and shift said sill to a bridging position during the vertical upward opening movement of said gate, and the other arm of said fork being engageable with said pawl to drive said link assembly, cooperate With said counterweight, and shift said sill to a blocking position during the vertical downward closing movement of said gate.

References Cited in the file of this patent UNITED STATES PATENTS 1,529,122 Fischer Mar. 10, 1925 1,763,858 Peele June 17, 1930 2,739,354 Pope .V. V Mar. ,27, 195.6 

